How is AND logic produced in a pneumatic circuit?

Two 3/2 valves are connected in series, so air passes only when both are operated. A press might need both a guard valve and a start button operated.

How is OR logic produced in a pneumatic circuit?

Two 3/2 valves feed the two inlets of a shuttle valve. Either valve can then operate the cylinder, as with buttons on both sides of a door.

How is NOT logic produced in a pneumatic circuit?

A normally open 3/2 valve gives an output until it is operated. The output is removed when the valve is operated, so the output is the inverse of the input.

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Mechanical and Pneumatic Components

Pneumatic circuits for logic, timing and speed control

3 things to know
AS 1 Paper 2

Overview

Direct and indirect control, double-pilot 5/2 circuits, AND, OR and NOT logic, time delays, speed control, air bleed sensors and automatic reciprocation.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Describe a circuit for the direct control of a single-acting cylinder.

Key term

Describe how two 3/2 push-button valves and a double-pilot 5/2 valve control a double-acting cylinder.

Key term

Why might a single-acting cylinder be controlled indirectly through a pilot-operated valve?

Questions from this subtopic

Each one with the model answer underneath.

1
Describe a circuit for the direct control of a single-acting cylinder.
Model answer
A 3/2 push-button valve is connected between the air supply and the cylinder. The cylinder extends while the button is held. The spring returns it when the button is released.
2
Why might a single-acting cylinder be controlled indirectly through a pilot-operated valve?
Model answer
A small push-button valve sends a pilot signal to a larger main valve. The operator's valve can then be small and remote, while the main valve handles the high flow.
3
Describe how two 3/2 push-button valves and a double-pilot 5/2 valve control a double-acting cylinder.
Model answer
One button pilots the 5/2 valve over so that the cylinder extends. The other button pilots it back so that the cylinder retracts. The cylinder holds its position between signals because the valve has memory.
4
How is AND logic produced in a pneumatic circuit?
Model answer
Two 3/2 valves are connected in series, so air passes only when both are operated. A press might need both a guard valve and a start button operated.
5
How is OR logic produced in a pneumatic circuit?
Model answer
Two 3/2 valves feed the two inlets of a shuttle valve. Either valve can then operate the cylinder, as with buttons on both sides of a door.
6
How is NOT logic produced in a pneumatic circuit?
Model answer
A normally open 3/2 valve gives an output until it is operated. The output is removed when the valve is operated, so the output is the inverse of the input.

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